Process of dewaxing mineral oils



Patented Mar. 5, 1935 PRQCESS 'OFDEWAXING MINERAL OILS Harry T.,Bemiett, Tulsa, Okla., assignor to .Mid-

Continent Petroleum Corporation, Tulsa, Okla, a corporation-of Delaware No Drawing. Application January .9, 1930,

Serial No. 419,747

9 Claims. (Cl. 196-19) This invention relatesto a process of removing so that the mixture containing the soap willnot waxfrom mineral oils, including petroleum vprodrevert back to its original state, that isthe wax ucts. More particularly it relates to a method will remain in suchcondition after treating that for removing crystal forming wax from,-petroit can be easily removed from the oil.

leum products, especially lubricating oil. The soap treatedoil is then diluted with a low 5 When the wax exists in .a petroleum oil in an boiling point hydrocarbon, such as petroleum amorphous state it can be readily removed" by naphtha. However, any suitable diluent maybe subjecting the oil to a centrifuging ,or similar used. The amount of diluentis preferably .apoperation. However, prior to this invention it proximately 40 to 80 percent ofthe volume of the 10 has been-extremely difficult ifnot impossible to resultant mixture. For example, there may be '10 remove the wax byv centrifuging when it exists in sixty gallons of naphtha to every forty gallons a crystalline state. The methods usedfor reof oil. moving amorphous waxwould not satisfactorily The resultant mixture is ;then;chilled to :a'temremove crystal-forming wax, and attempts to perature of about 10 above zero-to about 45 remove -,crystalrforming,qwax by centrifuging below zero F. 15

have proved commercially unsatisfactory. After chilling to the desired temperature, the

The object of this invention, therefore, isto mixture is subjected to centrifugal force and economically remove the wax in asimple manthe wax removed. ner, regardless of its previous structure. The low boiling :point' hydrocarbon is thenre- To the accomplishment of .the foregoing object moved from the oil by distillation, orin any 20 the invention comprises the steps hereinafter other suitable manner. described and more particularly pointed out in The remaining soap andstabilizer, if :a sepathe appended claims. 3 rate stabilizer is used, may. then be either re- An approved method of carrying out this invenmoved orleft in the oil as desired.

,tion is set forth in detail in the following .de- In the foregoing process the wax, :even though 25 scription, but it is to be understood'that this it originally {existed in a crystalline state will specific disclosure does not set forth allot-the beichanged in structure, :so that it can be-reasily. several ways in which the principle .of my invenremoved bycentrifuging ;in the manner ordition may be used, and that various modifications narily employed to remove amorphous-wax. The conforming to the invention will be obvious to advantages-lofsuch amocessare readily appar 30 those skilled in this art. out to those skilled in the art. 7 In the following description the method is set Petroleum oils containing crystal-forming wax forth as relating to lubricating oil. It is underare unsuited for use at a low temperature bestood, however, that this invention is not limited cause the wax will harden and prevent satisfacto removing wax from lubricating oil because tory use of the products. Since this invention 5 wax may be likewise removed from the other shows how crystal-forming wax may be easily, petroleum products. quickly and effectively removed, which was pre- 1 have found that the addition of a small viously thought commercially impossible, it is quantity of soap, such as aluminum stearate apparent that petroleum products which origi- 40 which is substantially insoluble in water to the nally contained crystal-forming wax can now be 40 lubricating oil containing the crystal-forming satisfactorily used at low temperatures.

wax will change the structure of the wax in such This invention is especia y Valuable in treating manner that the wax may be easily removed. lubricating oil distillates, as lubricating oils of The amount of soap to be used will vary with this kind which have been subjected to vaporizathe condition of the oil and the results desired. tion and condensation usually contain the crystal- 45 The amount, however, is preferably less than 2 forming wax, while the wax in the oils remainpercent of the weight of the mass and about 0.1 ing in the still is usually amorphous, or nonpercent will, under ordinary conditions, give satcrystalline, when the oils are chilled. However,

isfactory results. the invention may be used in treating any hydro- After the soap has been added to the oil it may carbon oil containing crystal-forming wax. 50 or may not be necessary to stabilize the re- As an example of one form of this invention, I

sultant mixture. If it is necessary to stabilize will describe one method of treating an oil having the mixture, the mixture may be heated to a a Saybolt universal viscosity of at 210 F. and

temperature of about 350 F., or aseparate stabia pour point of F. 'About 0.1 percent by 55 lizing agent, such as benzyl alcohol may be used weight of aluminum stearate was added to the 55 diluted with naphtha so that the resultant mixture contained 60 percent by volume of diluent.

, The resultant mixture was then chilled to 20 F.

and centrifuged to separate the mixture into two portions, i. e. oil and naphtha, and wax and naphtha. The naphtha was then removed from the oil by distillation. The finished oil had a pour point of F. and a Saybolt universal viscosity of 60 at 210 F.

I claim:

1. The method or" removing crystal-forming Wax from mineral oils, which comprises adding aluminum stearate and naphtha to the oil to be treated, chilling the resultant mixture, subjecting the chilled mixture to centrifugal force to remove the wax, and removing the naphtha from the dewaxed oil.

2. The method of removing crystal-forming wax from petroleum oils which comprises adding aluminum stearate to the oil to be treated to render the wax removable at low temperatures, diluting the product with a quantity of petroleum naphtha amounting to 40 to 80% of the volume of the resultant mixture, chilling said mixture, subjecting the same to centrifugal force to remove the wax, and removing said naphtha from said oil.

3. The method of removing crystal-forming wax from lubricating oil which comprises adding aluminum stearate to the oil to be treated to facilitate removal of the Wax at low temperatures, stabilizing the resultant mixture, diluting the oil with petroleum naphtha, chilling the mixture to a temperature from 10 above zero F. to about below zero 11, subjecting the chilled mixture to centrifugal force to remove the Wax, and removing said naphtha from said oil.

4. The method of removing crystal-forming Wax from lubricating oil which comprises preventing crystallization of the wax at low temperatures by adding less than 2% of aluminum stearate to the oil tobe treated, stabilizing the resultant mixture by heating the same, diluting the oil with a quantity of naphtha amounting to 40% to of the volume of the resultant mixture, chilling said resultant mixture to a temperature from 10 above zero to about 45 below zero F., then subjecting the same to centrifugal force to remove the wax, and removing said naphtha from said oil.

5. The method of removing crystal-forming wax from lubricating oil which comprises preventing crystallization of the wax at low temperatures by adding less than 2% of aluminum stearate to the oil to be treated, stabilizing the resultant mixture by heating the same to a temperature of about 350 F., diluting the oil with a quantity of petroleum naphtha amounting to 40% to 80% of the volume of the resultant mixture, chilling said mixture to a temperature from 10 above zero to about 45 below zero F., to remove the wax, and removing said naphtha and aluminum stearate from said oil.

6. The method of removing wax from petroleum products which comprises adding to the product to be treated a soap which is substantially insoluble in water to facilitate the removal of wax at low temperatures, chilling the resultant mixture, and removing the wax from said product.

7. The method of removing wax from petroleum products which comprises adding to the petroleum product a soap which is substantially insoluble in. water to facilitate the removal of wax at low temperatures, dilutingthe product with a low boiling point hydrocarbon oil, chilling the resultant mixture to a temperature between 10 above zero F. and about 45 below zero F., sub jecting the chilled mixture to centrifugal force to remove the wax, and removing said low boiling point hydrocarbon oil from said product.

8. The method of removing crystal-forming wax from petroleum oils which comprises adding to the oil to be treated a diluent and a soap which is substantially insoluble in water and which will affect the structure of the wax at low temperatures to facilitate the removal of wax in a centrifuge, chilling the resultant mixture to a relatively low temperature, subjecting the chilled mixture to centrifugal force to remove wax, and removing the diluent from said oil.

9. In the manufacture of low pour point lubricating oil from wax-containing mineral oils, the steps which comprise forming a mixture of a solvent, an oil containing wax and a small amount of aluminum stearate, chilling the mixture to precipitate the wax and separating the precipitated wax from the oil by centrifuging.

HARRY T.VBENNETT. 

